The present invention relates to a chromatography column for use in liquid chromatography systems, and more particularly to large columns having a diameter greater than approximately 50 mm.
A liquid chromatography system consists of the following major components: a pump, an injector, a column and a detector. Chromatographic separation occurs in the column when a solvent carrying a sample passes through porous media that is tightly packed in the column. This packed bed is retained in the column by filters that are being held by end caps. A poorly packed column, plugged filters, or a fouled bed will severely impair an analysis.
In general, there are two major designs of chromatographic columns. The first major design comprises a xe2x80x9csmallxe2x80x9d diameter (up to 30 mm) column having a tubular body with threaded ends that are capped by end-fittings. The second major design, as shown in FIG. 1, comprises a xe2x80x9clargexe2x80x9d diameter column (50 mm and up) having a tubular body with flanges welded to the tubular body. End-caps are attached to the flanges by bolts. Because conventional large diameter chromatography columns are expensive and bulky, it would be advantageous to extend the threaded column design to large diameter columns.
Unfortunately, there is one significant obstacle to implementing the threaded design with large diameter columns. It is very difficult to open a large column that utilizes a threaded design, and columns need to be opened from time to time so blocked filters can be replaced or the column can be repacked.
To open a large diameter, threaded column, a wrench must be utilized to apply unscrewing torque to the end-fittings. The magnitude of the required torque is exponentially proportional to the diameter of the thread. The torque required to open large diameter, threaded columns is so great, they have not been practical to use.
The present invention provides a large diameter chromatography column having a threaded design that can be easily opened by applying very moderate torque.
According to the invention, a large diameter chromatography column comprises a column body with threaded end portions. At each of the end portions, a respective filter housing is disposed. An end cap is threaded onto each of the threaded end portions. Each of the end caps has holes for receiving a plurality of mechanical fasteners. The mechanical fasteners apply pressure on the filter housing which forces it against the face of the column. When the need to open the column arises, the mechanical fasteners can be easily loosened to release the tension on the thread between column body and end cap. After this, the end cap can be unscrewed by hand without using any tools. Thus, the novel chromatography column of the present invention can be opened with minimal effort.
An advantage of the chromatography column of the present invention is that it can be easily opened for repacking and/or changing filters.
Another advantage of the chromatography column of the present invention is that it is much less expensive to manufacture than the flanged column of the same diameter.